As the nonprofit sector continues to grow in size and importance in American society, successful organizations proactively initiate strategic planning so they can be more responsive to changing circumstances, underlying trends, and shifting demands. At times, however, organizations develop elaborate plans that are never implemented. Unfortunately, there is less systematic research about strategic planning in the nonprofit sector than in the for-profit sector and even less research documenting whether or not the plans that get developed in nonprofit organizations actually get implemented. The purpose of this qualitative study was to understand how strategic planning improves the effectiveness of two nonprofit organizations that were studied, discern the processes used by the organizations to engage in strategic planning, and analyze the extent to which the plans were implemented. The study employed case study methodology and included a comparative examination of the processes used by the two nonprofit organizations that were studied to develop and implement strategic plans. Findings revealed that the planning processes in both organizations were relatively effective because both organizations took a collaborative approach to planning and adhered to clear timelines. Both organizations, for example, had a planning committee and facilitator to guide the process. By comparison, the implementation phase, especially in one of the organizations, was not clearly organized, had no clear timelines, and was not consistently monitored. Factors that facilitated successful implementation of the plans were: full and active executive support, the quality of the final written document, and engaged leadership. The absence of clear implementation of timelines and uncertainty of money and other resources appeared to be the major factors that inhibited implementation in both organizations. In addition, in one of the organizations, the CEO's leadership of the planning process also appeared to limit the involvement of other members of the organization which, in turn, resulted in implementation problems. This study contributes to the field since few empirical studies of strategic planning have been conducted in the nonprofit sector. Additionally, it serves as a useful tool for organizations that wish to undertake a successful strategic planning and implementation process to improve their effectiveness. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]